We consider solutions of the stationary Extended Fisher-Kolmogorov equation with general potential that are global minimizers of an associated variational problem. We present results that relate the global minimization property to a generalized concept of monotonicity of the solutions. This monotonicity can be described as the lack of intersections of the solution curve when projected onto the $(u,u')$--plane. Our method is based on applying a cut-and-paste argument in the space $H^2( {mathbb{R )$ to intersections in the $(u,u')$--plane. The statements and proofs are presented for the Extended Fisher-Kolmogorov equation, but the method can be directly extended to a wide class of fourth-order ordinary differential equations that derive from minimization problems.

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CWI
Modelling, Analysis and Simulation [MAS]

Peletier, M.A. (2000). Generalized monotonicity from global minimization in fourth-order ODEs. Modelling, Analysis and Simulation [MAS]. CWI.